Modeling of acoustic wave scattering from a two-dimensional fracture

We propose two possible representative models for a 2D fracture in reservoirs. The first one simulates the fracture as a low-aspect ratio elliptical cylinder. The inner properties of this elliptical cylinder are assumed to be homogeneous and different from the surrounding medium that is also homogenous. This model can approximately describe the actual shape of fractures observed in the field, and provides a clear physical sense of the distribution of the scattered energy over space. However, it lacks the detailed description of the fractures (micro fractures or cracks) and does not account for the effect of the rough contacting surfaces, which could greatly influence the stiffness or compliance of the fractures [Brown and Scholz (1985), Sevostianov et al., (2008), Romain et al., (2009)]. Ignoring these micro structures could result in an underestimation of the fracture stiffness. Our second model considers that a large fracture is composed of a sequence of smaller fracture. In this model the resulting fracture includes open and closed sections to capture some of the complexity of more realistic fracture geometries. Similar to the first model, the open crack sections are also modeled as lowaspect ratio elliptical cylinders, but with much smaller sizes.